Drama where second leads (who were in love with first leads) get together?

Hello! I've been scrolling through past topics but I couldn't find anything like what I'm looking for. 

I've just watched a drama where the SML is in love with the FFL, and the SFL is in love with FML, then after a while the second leads fall out of love with the firsts, and in love with each other (the drama is My Secret Romance!). 

So I was wondering if there are other dramas just like this. I hate to see the second leads end up sad and lonely at the end :(

Thank you!